Label	Element	Value
Risk/Return:	rr_RiskReturnAbstract
Registrant Name	dei_EntityRegistrantName	VANGUARD MUNICIPAL BOND FUNDS
Prospectus Date	rr_ProspectusDate	Feb. 26, 2016
Retail | Vanguard Tax-Exempt Money Market Fund
Risk/Return:	rr_RiskReturnAbstract
Risk/Return [Heading]	rr_RiskReturnHeading	Vanguard Tax-Exempt Money Market Fund
Objective [Heading]	rr_ObjectiveHeading	Investment Objective
Objective, Primary [Text Block]	rr_ObjectivePrimaryTextBlock	The Fund seeks to provide current income that is exempt from federal personal income taxes while maintaining liquidity and a stable share price of $1.
Expense [Heading]	rr_ExpenseHeading	Fees and Expenses
Expense Narrative [Text Block]	rr_ExpenseNarrativeTextBlock	The following table describes the fees and expenses you may pay if you buy and hold shares of the Fund.
Shareholder Fees Caption [Text]	rr_ShareholderFeesCaption	Shareholder Fees (Fees paid directly from your investment)
Operating Expenses Caption [Text]	rr_OperatingExpensesCaption	Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of the value of your investment)
Expense Example [Heading]	rr_ExpenseExampleHeading	Example
Expense Example Narrative [Text Block]	rr_ExpenseExampleNarrativeTextBlock	The following example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. It illustrates the hypothetical expenses that you would incur over various periods if you invested $10,000 in the Fund’s shares. This example assumes that the Fund provides a return of 5% each year and that total annual fund operating expenses remain as stated in the preceding table. You would incur these hypothetical expenses whether or not you redeem your investment at the end of the given period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading]	rr_StrategyHeading	Principal Investment Policies
Strategy Narrative [Text Block]	rr_StrategyNarrativeTextBlock	The Fund invests in a variety of high-quality, short-term municipal securities. To be considered high quality, a security generally must be rated in one of the two highest credit-quality categories for short-term securities by at least two nationally recognized rating services (or by one, if only one rating service has rated the security). If unrated, the security must be determined by Vanguard to be of quality equivalent to securities in the two highest credit-quality categories. The Fund invests in securities with effective maturities of 397 days or less, maintains a dollar-weighted average maturity of 60 days or less, and maintains a dollar-weighted average life of 120 days or less.
Risk [Heading]	rr_RiskHeading	Principal Risks
Risk Narrative [Text Block]	rr_RiskNarrativeTextBlock	The Fund is designed for investors with a low tolerance for risk; however, the Fund is subject to the following risks, which could affect the Fund’s performance: • Income risk, which is the chance that the Fund’s income will decline because of falling interest rates. Because the Fund’s income is based on short-term interest rates—which can fluctuate significantly over short periods—income risk is expected to be high. • Credit risk, which is the chance that the issuer of a security will fail to pay interest or principal in a timely manner or that negative perceptions of the issuer’s ability to make such payments will cause the price of that security to decline. Credit risk should be very low for the Fund because it invests primarily in securities that are considered to be of high quality. • Manager risk, which is the chance that poor security selection will cause the Fund to underperform relevant benchmarks or other funds with a similar investment objective. • Tax risk, which is the chance that all or a portion of the tax-exempt income from municipal bonds held by the Fund will be declared taxable, possibly with retroactive effect, because of unfavorable changes in tax laws, adverse interpretations by the Internal Revenue Service or state or local tax authorities, or noncompliant conduct of a bond issuer. • Derivatives risk. The Fund may invest in derivatives, which may involve risks different from, and possibly greater than, those of investments directly in the underlying securities, assets, or market indexes. An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency. Although the Fund seeks to preserve the value of your investment at $1 per share, it is possible to lose money by investing in the Fund.
Risk Money Market Fund [Text]	rr_RiskMoneyMarketFund	Although the Fund seeks to preserve the value of your investment at $1 per share, it is possible to lose money by investing in the Fund.
Risk Not Insured Depository Institution [Text]	rr_RiskNotInsuredDepositoryInstitution	An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table [Heading]	rr_BarChartAndPerformanceTableHeading	Annual Total Returns
Performance Narrative [Text Block]	rr_PerformanceNarrativeTextBlock	The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a comparative benchmark, which has investment characteristics similar to those of the Fund. Returns for the Tax-Exempt Money Market Funds Average are derived from data provided by Lipper, a Thomson Reuters Company. Keep in mind that the Fund’s past performance does not indicate how the Fund will perform in the future. Updated performance information is available on our website at vanguard.com/performance or by calling Vanguard toll-free at 800-662-7447.
Performance Information Illustrates Variability of Returns [Text]	rr_PerformanceInformationIllustratesVariabilityOfReturns	The following bar chart and table are intended to help you understand the risks of investing in the Fund. The bar chart shows how the performance of the Fund has varied from one calendar year to another over the periods shown. The table shows how the average annual total returns of the Fund compare with those of a comparative benchmark, which has investment characteristics similar to those of the Fund.
Performance Availability Phone [Text]	rr_PerformanceAvailabilityPhone	800-662-7447
Performance Availability Website Address [Text]	rr_PerformanceAvailabilityWebSiteAddress	vanguard.com/performance
Performance Past Does Not Indicate Future [Text]	rr_PerformancePastDoesNotIndicateFuture	Keep in mind that the Fund’s past performance does not indicate how the Fund will perform in the future.
Bar Chart [Heading]	rr_BarChartHeading	Annual Total Returns — Vanguard Tax-Exempt Money Market Fund Investor Shares
Bar Chart Closing [Text Block]	rr_BarChartClosingTextBlock	During the periods shown in the bar chart, the highest return for a calendar quarter was 0.92% (quarter ended September 30, 2007), and the lowest return for a quarter was 0.00% (quarter ended March 31, 2014).
Performance Table Heading	rr_PerformanceTableHeading	Average Annual Total Returns for Periods Ended December 31, 2015
Retail | Vanguard Tax-Exempt Money Market Fund | Investor Shares
Risk/Return:	rr_RiskReturnAbstract
Purchase Fee	rr_MaximumCumulativeSalesChargeOverOther	none
Sales Charge (Load) Imposed on Purchases	rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice	none
Sales Charge (Load) Imposed on Reinvested Dividends	rr_MaximumSalesChargeOnReinvestedDividendsAndDistributionsOverOther	none
Redemption Fee	rr_RedemptionFeeOverRedemption	none
Account Service Fee (for certain fund account balances below $10,000)	rr_MaximumAccountFee	$ 20	[1]
Management Fees	rr_ManagementFeesOverAssets	0.13%
12b-1 Distribution Fee	rr_DistributionAndService12b1FeesOverAssets	none
Other Expenses	rr_OtherExpensesOverAssets	0.02%
Total Annual Fund Operating Expenses	rr_ExpensesOverAssets	0.15%	[2]
1 Year	rr_ExpenseExampleYear01	$ 15
3 Years	rr_ExpenseExampleYear03	48
5 Years	rr_ExpenseExampleYear05	85
10 Years	rr_ExpenseExampleYear10	192
1 Year	rr_ExpenseExampleNoRedemptionYear01	15
3 Years	rr_ExpenseExampleNoRedemptionYear03	48
5 Years	rr_ExpenseExampleNoRedemptionYear05	85
10 Years	rr_ExpenseExampleNoRedemptionYear10	$ 192
2006	rr_AnnualReturn2006	3.37%
2007	rr_AnnualReturn2007	3.62%
2008	rr_AnnualReturn2008	2.27%
2009	rr_AnnualReturn2009	0.41%
2010	rr_AnnualReturn2010	0.14%
2011	rr_AnnualReturn2011	0.06%
2012	rr_AnnualReturn2012	0.04%
2013	rr_AnnualReturn2013	0.01%
2014	rr_AnnualReturn2014	0.01%
2015	rr_AnnualReturn2015	0.01%
Highest Quarterly Return, Label	rr_HighestQuarterlyReturnLabel	highest return
Highest Quarterly Return, Date	rr_BarChartHighestQuarterlyReturnDate	Sep. 30, 2007
Highest Quarterly Return	rr_BarChartHighestQuarterlyReturn	0.92%
Lowest Quarterly Return, Label	rr_LowestQuarterlyReturnLabel	lowest return
Lowest Quarterly Return, Date	rr_BarChartLowestQuarterlyReturnDate	Mar. 31, 2014
Lowest Quarterly Return	rr_BarChartLowestQuarterlyReturn	none
1 Year	rr_AverageAnnualReturnYear01	0.01%
5 Years	rr_AverageAnnualReturnYear05	0.03%
10 Years	rr_AverageAnnualReturnYear10	0.99%
Retail | Vanguard Tax-Exempt Money Market Fund | Tax-Exempt Money Market Funds Average
Risk/Return:	rr_RiskReturnAbstract
1 Year	rr_AverageAnnualReturnYear01	0.01%
5 Years	rr_AverageAnnualReturnYear05	0.01%
10 Years	rr_AverageAnnualReturnYear10	0.75%

[1] /year

[2] Vanguard and the Fund's board have voluntarily agreed to temporarily limit certain net operating expenses in excess of the Fund's daily yield so as to maintain a zero or positive yield for the Fund. Vanguard and the Fund's board may terminate the temporary expense limitation at any time.